Needleless injection ports are frequently used in the medical industry for ready access to infusion lines. Broadly speaking, backcheck valves or needleless injection ports comprise quick-connect valves that permit medication or the like to be injected into infusion lines via a syringe and then close automatically when the syringe is withdrawn from the valve.
Representative prior U.S. Patents include U.S. Pat. Nos. 3,570,484, 3,831,629, 5,006,114, 5,049,128, 5,147,333, 5,201,725, 5,242,432, and 5,439,451. The contents of these patents are expressly incorporated herein by reference.
Regarding the needleless injection ports disclosed in U.S. Pat. No. 5,439,451, experience has shown that when a syringe is inserted into the injection port, the flexible elastomer piston 30 disclosed in the '451 patent occasionally sticks or does not readily re-seal upon withdrawing the syringe. Therefore, lubricant is typically added to the piston surface in the commercial embodiment to minimize friction between the piston 30 and the interior surface of the housing 10 to ensure proper seating of the main seal 68 and the conical shoulder 72 of the outer body 10 when the syringe is removed. However, adding a lubricant to the injection port involves an added step and negatively impacts the bottom line. In addition, the added step increases the risk of contamination to the valve and the risk of using a wrong lubricant.
Accordingly, there is a need for an improved piston that closes without the use of external lubricants.